A DCO is a component of an all-digital phase locked loop (ADPLL), which is commonly used in advanced CMOS technology. DCOs can be implemented in a variety of ways. An LC-based DCO, one type of DCO, can often achieve better phase noise (PN), lower power consumption, lower frequency pushing, and greater resistance to process and temperature variations than its counterparts.
An LC-based DCO utilizes an arrangement of one or more capacitors to control its frequency (e.g., using a bank of tuning capacitors). A capacitor tuning bank of an LC-based DCO is often implemented using a binary weighting technique. A binary weighted design offers a typically more compact layout, compared to other techniques, e.g., thermal meter arrangements, at the cost of linearity. Non-linearity of a binary weighted design can result in phase error in the DCO output.